/*
 * jcparam.c
 *
 * Copyright (C) 1991-1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains optional default-setting code for the JPEG compressor.
 * Applications do not have to use this file, but those that don't use it
 * must know a lot more about the innards of the JPEG code.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/*
 * Quantization table setup routines
 */

GLOBAL void
jpeg_add_quant_table( j_compress_ptr cinfo, int which_tbl,
                      const unsigned int * basic_table,
                      int scale_factor, boolean force_baseline ) {
/* Define a quantization table equal to the basic_table times
 * a scale factor (given as a percentage).
 * If force_baseline is TRUE, the computed quantization table entries
 * are limited to 1..255 for JPEG baseline compatibility.
 */
    JQUANT_TBL ** qtblptr = &cinfo->quant_tbl_ptrs[which_tbl];
    int i;
    long temp;

    /* Safety check to ensure start_compress not called yet. */
    if ( cinfo->global_state != CSTATE_START ) {
        ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
    }

    if ( *qtblptr == NULL ) {
        *qtblptr = jpeg_alloc_quant_table( (j_common_ptr) cinfo );
    }

    for ( i = 0; i < DCTSIZE2; i++ ) {
        temp = ( (long) basic_table[i] * scale_factor + 50L ) / 100L;
        /* limit the values to the valid range */
        if ( temp <= 0L ) {
            temp = 1L;
        }
        if ( temp > 32767L ) {
            temp = 32767L;
        }                             /* max quantizer needed for 12 bits */
        if ( ( force_baseline ) && ( temp > 255L ) ) {
            temp = 255L;
        }               /* limit to baseline range if requested */
        ( *qtblptr )->quantval[i] = (UINT16) temp;
    }

    /* Initialize sent_table FALSE so table will be written to JPEG file. */
    ( *qtblptr )->sent_table = FALSE;
}


GLOBAL void
jpeg_set_linear_quality( j_compress_ptr cinfo, int scale_factor,
                         boolean force_baseline ) {
/* Set or change the 'quality' (quantization) setting, using default tables
 * and a straight percentage-scaling quality scale.  In most cases it's better
 * to use jpeg_set_quality (below); this entry point is provided for
 * applications that insist on a linear percentage scaling.
 */
/* This is the sample quantization table given in the JPEG spec section K.1,
 * but expressed in zigzag order (as are all of our quant. tables).
 * The spec says that the values given produce "good" quality, and
 * when divided by 2, "very good" quality.
 */
    static const unsigned int std_luminance_quant_tbl[DCTSIZE2] = {
        16,  11,  12,  14,  12,  10,  16,  14,
        13,  14,  18,  17,  16,  19,  24,  40,
        26,  24,  22,  22,  24,  49,  35,  37,
        29,  40,  58,  51,  61,  60,  57,  51,
        56,  55,  64,  72,  92,  78,  64,  68,
        87,  69,  55,  56,  80, 109,  81,  87,
        95,  98, 103, 104, 103,  62,  77, 113,
        121, 112, 100, 120,  92, 101, 103,  99
    };
    static const unsigned int std_chrominance_quant_tbl[DCTSIZE2] = {
        17,  18,  18,  24,  21,  24,  47,  26,
        26,  47,  99,  66,  56,  66,  99,  99,
        99,  99,  99,  99,  99,  99,  99,  99,
        99,  99,  99,  99,  99,  99,  99,  99,
        99,  99,  99,  99,  99,  99,  99,  99,
        99,  99,  99,  99,  99,  99,  99,  99,
        99,  99,  99,  99,  99,  99,  99,  99,
        99,  99,  99,  99,  99,  99,  99,  99
    };

    /* Set up two quantization tables using the specified scaling */
    jpeg_add_quant_table( cinfo, 0, std_luminance_quant_tbl,
                          scale_factor, force_baseline );
    jpeg_add_quant_table( cinfo, 1, std_chrominance_quant_tbl,
                          scale_factor, force_baseline );
}


GLOBAL int
jpeg_quality_scaling( int quality ) {
/* Convert a user-specified quality rating to a percentage scaling factor
 * for an underlying quantization table, using our recommended scaling curve.
 * The input 'quality' factor should be 0 (terrible) to 100 (very good).
 */
/* Safety limit on quality factor.  Convert 0 to 1 to avoid zero divide. */
    if ( quality <= 0 ) {
        quality = 1;
    }
    if ( quality > 100 ) {
        quality = 100;
    }

    /* The basic table is used as-is (scaling 100) for a quality of 50.
     * Qualities 50..100 are converted to scaling percentage 200 - 2*Q;
     * note that at Q=100 the scaling is 0, which will cause j_add_quant_table
     * to make all the table entries 1 (hence, no quantization loss).
     * Qualities 1..50 are converted to scaling percentage 5000/Q.
     */
    if ( quality < 50 ) {
        quality = 5000 / quality;
    } else {
        quality = 200 - quality * 2;
    }

    return quality;
}


GLOBAL void
jpeg_set_quality( j_compress_ptr cinfo, int quality, boolean force_baseline ) {
/* Set or change the 'quality' (quantization) setting, using default tables.
 * This is the standard quality-adjusting entry point for typical user
 * interfaces; only those who want detailed control over quantization tables
 * would use the preceding three routines directly.
 */
/* Convert user 0-100 rating to percentage scaling */
    quality = jpeg_quality_scaling( quality );

    /* Set up standard quality tables */
    jpeg_set_linear_quality( cinfo, quality, force_baseline );
}


/*
 * Huffman table setup routines
 */

LOCAL void
add_huff_table( j_compress_ptr cinfo,
                JHUFF_TBL ** htblptr, const UINT8 * bits, const UINT8 * val ) {
/* Define a Huffman table */
    if ( *htblptr == NULL ) {
        *htblptr = jpeg_alloc_huff_table( (j_common_ptr) cinfo );
    }

    MEMCOPY( ( *htblptr )->bits, bits, SIZEOF( ( *htblptr )->bits ) );
    MEMCOPY( ( *htblptr )->huffval, val, SIZEOF( ( *htblptr )->huffval ) );

    /* Initialize sent_table FALSE so table will be written to JPEG file. */
    ( *htblptr )->sent_table = FALSE;
}


LOCAL void
std_huff_tables( j_compress_ptr cinfo ) {
/* Set up the standard Huffman tables (cf. JPEG standard section K.3) */
/* IMPORTANT: these are only valid for 8-bit data precision! */
    static const UINT8 bits_dc_luminance[17] =
    { /* 0-base */ 0, 0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0 };
    static const UINT8 val_dc_luminance[] =
    { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };

    static const UINT8 bits_dc_chrominance[17] =
    { /* 0-base */ 0, 0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 };
    static const UINT8 val_dc_chrominance[] =
    { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };

    static const UINT8 bits_ac_luminance[17] =
    { /* 0-base */ 0, 0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 0x7d };
    static const UINT8 val_ac_luminance[] =
    { 0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,
      0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
      0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08,
      0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0,
      0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16,
      0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,
      0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
      0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
      0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
      0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
      0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
      0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
      0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
      0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
      0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
      0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5,
      0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4,
      0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2,
      0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,
      0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
      0xf9, 0xfa };

    static const UINT8 bits_ac_chrominance[17] =
    { /* 0-base */ 0, 0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 0x77 };
    static const UINT8 val_ac_chrominance[] =
    { 0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,
      0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,
      0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91,
      0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0,
      0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34,
      0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26,
      0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38,
      0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
      0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
      0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
      0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
      0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
      0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96,
      0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,
      0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4,
      0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3,
      0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2,
      0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda,
      0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9,
      0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
      0xf9, 0xfa };

    add_huff_table( cinfo, &cinfo->dc_huff_tbl_ptrs[0],
                    bits_dc_luminance, val_dc_luminance );
    add_huff_table( cinfo, &cinfo->ac_huff_tbl_ptrs[0],
                    bits_ac_luminance, val_ac_luminance );
    add_huff_table( cinfo, &cinfo->dc_huff_tbl_ptrs[1],
                    bits_dc_chrominance, val_dc_chrominance );
    add_huff_table( cinfo, &cinfo->ac_huff_tbl_ptrs[1],
                    bits_ac_chrominance, val_ac_chrominance );
}


/*
 * Default parameter setup for compression.
 *
 * Applications that don't choose to use this routine must do their
 * own setup of all these parameters.  Alternately, you can call this
 * to establish defaults and then alter parameters selectively.  This
 * is the recommended approach since, if we add any new parameters,
 * your code will still work (they'll be set to reasonable defaults).
 */

GLOBAL void
jpeg_set_defaults( j_compress_ptr cinfo ) {
    int i;

    /* Safety check to ensure start_compress not called yet. */
    if ( cinfo->global_state != CSTATE_START ) {
        ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
    }

    /* Allocate comp_info array large enough for maximum component count.
     * Array is made permanent in case application wants to compress
     * multiple images at same param settings.
     */
    if ( cinfo->comp_info == NULL ) {
        cinfo->comp_info = (jpeg_component_info *)
                           ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_PERMANENT,
                                                        MAX_COMPONENTS * SIZEOF( jpeg_component_info ) );
    }

    /* Initialize everything not dependent on the color space */

    cinfo->data_precision = BITS_IN_JSAMPLE;
    /* Set up two quantization tables using default quality of 75 */
    jpeg_set_quality( cinfo, 75, TRUE );
    /* Set up two Huffman tables */
    std_huff_tables( cinfo );

    /* Initialize default arithmetic coding conditioning */
    for ( i = 0; i < NUM_ARITH_TBLS; i++ ) {
        cinfo->arith_dc_L[i] = 0;
        cinfo->arith_dc_U[i] = 1;
        cinfo->arith_ac_K[i] = 5;
    }

    /* Default is no multiple-scan output */
    cinfo->scan_info = NULL;
    cinfo->num_scans = 0;

    /* Expect normal source image, not raw downsampled data */
    cinfo->raw_data_in = FALSE;

    /* Use Huffman coding, not arithmetic coding, by default */
    cinfo->arith_code = FALSE;

    /* By default, don't do extra passes to optimize entropy coding */
    cinfo->optimize_coding = FALSE;
    /* The standard Huffman tables are only valid for 8-bit data precision.
     * If the precision is higher, force optimization on so that usable
     * tables will be computed.  This test can be removed if default tables
     * are supplied that are valid for the desired precision.
     */
    if ( cinfo->data_precision > 8 ) {
        cinfo->optimize_coding = TRUE;
    }

    /* By default, use the simpler non-cosited sampling alignment */
    cinfo->CCIR601_sampling = FALSE;

    /* No input smoothing */
    cinfo->smoothing_factor = 0;

    /* DCT algorithm preference */
    cinfo->dct_method = JDCT_DEFAULT;

    /* No restart markers */
    cinfo->restart_interval = 0;
    cinfo->restart_in_rows = 0;

    /* Fill in default JFIF marker parameters.  Note that whether the marker
     * will actually be written is determined by jpeg_set_colorspace.
     */
    cinfo->density_unit = 0;/* Pixel size is unknown by default */
    cinfo->X_density = 1;   /* Pixel aspect ratio is square by default */
    cinfo->Y_density = 1;

    /* Choose JPEG colorspace based on input space, set defaults accordingly */

    jpeg_default_colorspace( cinfo );
}


/*
 * Select an appropriate JPEG colorspace for in_color_space.
 */

GLOBAL void
jpeg_default_colorspace( j_compress_ptr cinfo ) {
    switch ( cinfo->in_color_space ) {
        case JCS_GRAYSCALE:
            jpeg_set_colorspace( cinfo, JCS_GRAYSCALE );
            break;
        case JCS_RGB:
            jpeg_set_colorspace( cinfo, JCS_YCbCr );
            break;
        case JCS_YCbCr:
            jpeg_set_colorspace( cinfo, JCS_YCbCr );
            break;
        case JCS_CMYK:
            jpeg_set_colorspace( cinfo, JCS_CMYK );/* By default, no translation */
            break;
        case JCS_YCCK:
            jpeg_set_colorspace( cinfo, JCS_YCCK );
            break;
        case JCS_UNKNOWN:
            jpeg_set_colorspace( cinfo, JCS_UNKNOWN );
            break;
        default:
            ERREXIT( cinfo, JERR_BAD_IN_COLORSPACE );
    }
}


/*
 * Set the JPEG colorspace, and choose colorspace-dependent default values.
 */

GLOBAL void
jpeg_set_colorspace( j_compress_ptr cinfo, J_COLOR_SPACE colorspace ) {
    jpeg_component_info * compptr;
    int ci;

#define SET_COMP( index, id, hsamp, vsamp, quant, dctbl, actbl )  \
    ( compptr = &cinfo->comp_info[index], \
     compptr->component_id = ( id ), \
     compptr->h_samp_factor = ( hsamp ), \
     compptr->v_samp_factor = ( vsamp ), \
     compptr->quant_tbl_no = ( quant ), \
     compptr->dc_tbl_no = ( dctbl ), \
     compptr->ac_tbl_no = ( actbl ) )

    /* Safety check to ensure start_compress not called yet. */
    if ( cinfo->global_state != CSTATE_START ) {
        ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
    }

    /* For all colorspaces, we use Q and Huff tables 0 for luminance components,
     * tables 1 for chrominance components.
     */

    cinfo->jpeg_color_space = colorspace;

    cinfo->write_JFIF_header = FALSE;/* No marker for non-JFIF colorspaces */
    cinfo->write_Adobe_marker = FALSE;/* write no Adobe marker by default */

    switch ( colorspace ) {
        case JCS_GRAYSCALE:
            cinfo->write_JFIF_header = TRUE;/* Write a JFIF marker */
            cinfo->num_components = 1;
            /* JFIF specifies component ID 1 */
            SET_COMP( 0, 1, 1, 1, 0, 0, 0 );
            break;
        case JCS_RGB:
            cinfo->write_Adobe_marker = TRUE;/* write Adobe marker to flag RGB */
            cinfo->num_components = 3;
            SET_COMP( 0, 0x52 /* 'R' */, 1, 1, 0, 0, 0 );
            SET_COMP( 1, 0x47 /* 'G' */, 1, 1, 0, 0, 0 );
            SET_COMP( 2, 0x42 /* 'B' */, 1, 1, 0, 0, 0 );
            break;
        case JCS_YCbCr:
            cinfo->write_JFIF_header = TRUE;/* Write a JFIF marker */
            cinfo->num_components = 3;
            /* JFIF specifies component IDs 1,2,3 */
            /* We default to 2x2 subsamples of chrominance */
            SET_COMP( 0, 1, 2, 2, 0, 0, 0 );
            SET_COMP( 1, 2, 1, 1, 1, 1, 1 );
            SET_COMP( 2, 3, 1, 1, 1, 1, 1 );
            break;
        case JCS_CMYK:
            cinfo->write_Adobe_marker = TRUE;/* write Adobe marker to flag CMYK */
            cinfo->num_components = 4;
            SET_COMP( 0, 0x43 /* 'C' */, 1, 1, 0, 0, 0 );
            SET_COMP( 1, 0x4D /* 'M' */, 1, 1, 0, 0, 0 );
            SET_COMP( 2, 0x59 /* 'Y' */, 1, 1, 0, 0, 0 );
            SET_COMP( 3, 0x4B /* 'K' */, 1, 1, 0, 0, 0 );
            break;
        case JCS_YCCK:
            cinfo->write_Adobe_marker = TRUE;/* write Adobe marker to flag YCCK */
            cinfo->num_components = 4;
            SET_COMP( 0, 1, 2, 2, 0, 0, 0 );
            SET_COMP( 1, 2, 1, 1, 1, 1, 1 );
            SET_COMP( 2, 3, 1, 1, 1, 1, 1 );
            SET_COMP( 3, 4, 2, 2, 0, 0, 0 );
            break;
        case JCS_UNKNOWN:
            cinfo->num_components = cinfo->input_components;
            if ( ( cinfo->num_components < 1 ) || ( cinfo->num_components > MAX_COMPONENTS ) ) {
                ERREXIT2( cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
                          MAX_COMPONENTS );
            }
            for ( ci = 0; ci < cinfo->num_components; ci++ ) {
                SET_COMP( ci, ci, 1, 1, 0, 0, 0 );
            }
            break;
        default:
            ERREXIT( cinfo, JERR_BAD_J_COLORSPACE );
    }
}


#ifdef C_PROGRESSIVE_SUPPORTED

LOCAL jpeg_scan_info *
fill_a_scan( jpeg_scan_info * scanptr, int ci,
             int Ss, int Se, int Ah, int Al ) {
/* Support routine: generate one scan for specified component */
    scanptr->comps_in_scan = 1;
    scanptr->component_index[0] = ci;
    scanptr->Ss = Ss;
    scanptr->Se = Se;
    scanptr->Ah = Ah;
    scanptr->Al = Al;
    scanptr++;
    return scanptr;
}

LOCAL jpeg_scan_info *
fill_scans( jpeg_scan_info * scanptr, int ncomps,
            int Ss, int Se, int Ah, int Al ) {
/* Support routine: generate one scan for each component */
    int ci;

    for ( ci = 0; ci < ncomps; ci++ ) {
        scanptr->comps_in_scan = 1;
        scanptr->component_index[0] = ci;
        scanptr->Ss = Ss;
        scanptr->Se = Se;
        scanptr->Ah = Ah;
        scanptr->Al = Al;
        scanptr++;
    }
    return scanptr;
}

LOCAL jpeg_scan_info *
fill_dc_scans( jpeg_scan_info * scanptr, int ncomps, int Ah, int Al ) {
/* Support routine: generate interleaved DC scan if possible, else N scans */
    int ci;

    if ( ncomps <= MAX_COMPS_IN_SCAN ) {
        /* Single interleaved DC scan */
        scanptr->comps_in_scan = ncomps;
        for ( ci = 0; ci < ncomps; ci++ ) {
            scanptr->component_index[ci] = ci;
        }
        scanptr->Ss = scanptr->Se = 0;
        scanptr->Ah = Ah;
        scanptr->Al = Al;
        scanptr++;
    } else {
        /* Noninterleaved DC scan for each component */
        scanptr = fill_scans( scanptr, ncomps, 0, 0, Ah, Al );
    }
    return scanptr;
}


/*
 * Create a recommended progressive-JPEG script.
 * cinfo->num_components and cinfo->jpeg_color_space must be correct.
 */

GLOBAL void
jpeg_simple_progression( j_compress_ptr cinfo ) {
    int ncomps = cinfo->num_components;
    int nscans;
    jpeg_scan_info * scanptr;

    /* Safety check to ensure start_compress not called yet. */
    if ( cinfo->global_state != CSTATE_START ) {
        ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
    }

    /* Figure space needed for script.  Calculation must match code below! */
    if ( ( ncomps == 3 ) && ( cinfo->jpeg_color_space == JCS_YCbCr ) ) {
        /* Custom script for YCbCr color images. */
        nscans = 10;
    } else {
        /* All-purpose script for other color spaces. */
        if ( ncomps > MAX_COMPS_IN_SCAN ) {
            nscans = 6 * ncomps;
        }                   /* 2 DC + 4 AC scans per component */
        else {
            nscans = 2 + 4 * ncomps;
        }                       /* 2 DC scans; 4 AC scans per component */
    }

    /* Allocate space for script. */
    /* We use permanent pool just in case application re-uses script. */
    scanptr = (jpeg_scan_info *)
              ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_PERMANENT,
                                           nscans * SIZEOF( jpeg_scan_info ) );
    cinfo->scan_info = scanptr;
    cinfo->num_scans = nscans;

    if ( ( ncomps == 3 ) && ( cinfo->jpeg_color_space == JCS_YCbCr ) ) {
        /* Custom script for YCbCr color images. */
        /* Initial DC scan */
        scanptr = fill_dc_scans( scanptr, ncomps, 0, 1 );
        /* Initial AC scan: get some luma data out in a hurry */
        scanptr = fill_a_scan( scanptr, 0, 1, 5, 0, 2 );
        /* Chroma data is too small to be worth expending many scans on */
        scanptr = fill_a_scan( scanptr, 2, 1, 63, 0, 1 );
        scanptr = fill_a_scan( scanptr, 1, 1, 63, 0, 1 );
        /* Complete spectral selection for luma AC */
        scanptr = fill_a_scan( scanptr, 0, 6, 63, 0, 2 );
        /* Refine next bit of luma AC */
        scanptr = fill_a_scan( scanptr, 0, 1, 63, 2, 1 );
        /* Finish DC successive approximation */
        scanptr = fill_dc_scans( scanptr, ncomps, 1, 0 );
        /* Finish AC successive approximation */
        scanptr = fill_a_scan( scanptr, 2, 1, 63, 1, 0 );
        scanptr = fill_a_scan( scanptr, 1, 1, 63, 1, 0 );
        /* Luma bottom bit comes last since it's usually largest scan */
        scanptr = fill_a_scan( scanptr, 0, 1, 63, 1, 0 );
    } else {
        /* All-purpose script for other color spaces. */
        /* Successive approximation first pass */
        scanptr = fill_dc_scans( scanptr, ncomps, 0, 1 );
        scanptr = fill_scans( scanptr, ncomps, 1, 5, 0, 2 );
        scanptr = fill_scans( scanptr, ncomps, 6, 63, 0, 2 );
        /* Successive approximation second pass */
        scanptr = fill_scans( scanptr, ncomps, 1, 63, 2, 1 );
        /* Successive approximation final pass */
        scanptr = fill_dc_scans( scanptr, ncomps, 1, 0 );
        scanptr = fill_scans( scanptr, ncomps, 1, 63, 1, 0 );
    }
}

#endif /* C_PROGRESSIVE_SUPPORTED */
